Lead gauge for threads



Ff'o. 'HOAGLAND.

LEAD GAUGE FOR THREADS.

. I K APPLICATION FILED MAR. 16, me.

1 434 699. I Patented Nov. 7, 1922'.

. v 1 J- I U F 6 73 5 4 A C m l/VVEIV TOR TT mm Patented Nov. 7, lQZZ.

Ul i'hittt t dit hhl'l FRANK O. I-IOAGLAND, OF HARTFORD, CONNECTICUT,ASSIGNOR TO PRATT & "WHITNEY COMPANY, OF NEW YORK, N. Y., A CORPORATIONOF NEW JERSEY.

7 LEAD GAUGE FOR THREADS.

Application filed March 16, 1918. Serial No. 222,868.

T 0 all whom it may concern:

Be it known that I, FRANK O. HOAGLAND, a citizen of the United States,residing at Hartford, in the county of Hartford and State ofConnecticut, have invented certain new and useful Improvements in LeadGauges for Threads, of which the following is a specification.

The invention relates to a gauge which is adapted for easily andaccuratelymeasuring the lead of the threads on any externally threadedobject, being capable of use for all kinds of threads and all diameters.The object of the invention is to provide means whereby the lead may bemeasured substantially directly with minimum opportunity for error.

In the accompanying drawing I have shown the embodiment of the inventionwhich I now deem preferable, but it will be understood that changes andmodifications may be made within the scope of the appended claimswithout departing from the spirit of the invention. I

Of the drawing: I

Fig. 1 is a View illustrating the manner of use of a gauge embodying theinvention.

Fig. 2 is a plan view, on an enlarged scale, showing the gauge appliedto the threads of a thread gauge.

Fig. 3 is a vertical sectional view taken along the line 3,3 of Fig. 2.

Fig. 4: is an end view.

' Fig-. 5 isa bottom view.

Referring to the drawing, it will be seen that the gauge comprises twoparallel pins 1 and 2 having conical end parts each of which is adaptedto enter and fit the groove between two adjacent thread convolutions.The two pins are adjustable toward and from each other as required. Thecylindrical body parts of the pins are accurately ground to apredetermined diameter and the distance between their outermost sidescan be directly measured by a suitable measuring device, such as themicrometer calipers, M, indicated by dot-and-dash lines in Fig. 2. Itwillbe obvious that the micrometer reading, minus thevdiameter of one ofthe pins, will be. the exact distance between the two grooves beingmeasured. By moving the pins to fit different grooves and by turning thethreaded object as required, the thread maybe thoroughly explored andany errors of pitch observed and measured.

The devices for holding and relatively movmg the two pins 1 and 2 mayvary widely, but I prefer devices such as shown in the drawing. Asillustrated, the two pins are carried by supports 3 and 4 which comprisetelescopically connected blocks, one of them having an extension 5 whichprojects through and fits an aperture in the other. Projectinghorizontally from the support 3 is an arm 6 having an upturned end. Thisupturned end servesas a bearing for a screw 7 having threaded engagementwith the end part of the extension 5. Itwill be clear that by turningthe screw 7 the support 4 may be moved toward or away from the support3. For locking the two supports in adjusted posit-ion there is provideda shoe 8 which engages the extension 5 and which is adapted to be firmlyclamped against the extension by means of screws 9, 9 having knurledheads. Preferably, in order to take up any lost motion that may bepresent between the screw 7 and the extension 5, the extension and thesupport 4 are provided with a central longitudinal aperture in which ispositioned a coil compressing spring 10. This spring abuts at itsleft-hand end against a block 10 which is engaged by the screw 7 andabuts at its right-hand end against a screw 11 threaded into the end ofthe aperture in the support 4.

Preferably the supports 3 and 4 are provided with feet 12, 12 and 13, 13which serve to hold the supports with their main bottom surfaces out ofengagement with the surface on which the supports rest. For holding the,respective pins the sup-ports are provided respectively with downwardopening notches 1 and 2 having oppositely inclined surfaces adapted toengage the upper surfaces of the pins. Each support is provided with aplate 14; adapted to engage the lower surface of the corresponding pin,this plate being held in position by a screw 15. Preferably each platehas bosses 14 on its upper side so that it engages the corresponding pinat the ends only. It will be clear that by turning the screw 15 theplate be loosened to permit the pin to beremoved and another pinsubstituted.

Preferably, in using the gauge, a threaded object A to be gaged ismounted between suitable centers B, U, as shown in Fig. 1. A plate 1) isprovided having its upper surface horizontal and at an elevation whichis below the level of the axis oi the centers by a distance equal tothat between the arses or the pins and the bottom plane oi the feet 12,12 and and l3, 13. The result that when the gauge is placed on the plate3.) the pins are held with their axes in the same horizontal plane asthe axis of the threaded object A. The operator then carefully pushesthe gauge against the threads, adjusting the distance between the pinsso that they exactly enter and lit the grooves. In securing theadjustment the operator preterably makes use of a light or a white sheetof paper placed immediately beneath the pins, thus enabling him toobserve accurately any :t'ailure of the pins to closely ht the surfacesof the grooves. After the adjustment has-been secured the screws 9, 9are tightened and, it necessary, a further test is made to make surethat the pins have not been disturbed by the clamping operation. Then bymeans of the micrometer, as indicated. the distance between the pins ismeasured and the diameter of one of the pine is subtracted from thereading. The resulting distance compared with the true nominal distancebetween the grooves entered by the pinsand the difference between thesetwo distances is the error in the lead at the position of measurement.

It will be observed that inasmuch as the distance between the outersurfaces of the pins is measured at a position close to the points thereis a minimum opportunity for error arising from any possible inaccuracyin the adjustment of the pins or in the construction of the other partsof the gauge. By modern methods it is possible to term. the pins soaccurately that any errors in their diameters or in the concentric-ityot the points with respect to the'bodies ot the pins will be entirelynegligible The other parts of the gauge are also accurately constructed,but it will be clear that a minor error; as tor instance av slightdeviation from parallelism between the two pins, would make practicallyno difference in the resulting measurement. It the pins are accuratelyformed as stated, the measurements taken by the micrometer calipers orother measuring device will be accurate within the limits of scen racyof the device used.

V] hat I claim is:

1. In a gauge of the class described, the combination or two parallelpins each having a cylindrical body part accurately formed to apredetermined diameter and each having a conical end part concentricwith the body part and adapted to eXactlyfit the groove between twothread convolutions; supports for holding the respective pins at thesame distance from a common supporting surface, each support comprisinga block having a downward opening V-shaped notch for receiving thecorresponding pin .anda plate for engaging the pin to hold it in place,and means for relatively adjusting the two supports to change thedistance between the pins while maintaining them parallel.

2. in a gauge of the class described. the combination of two parallelpins each having a cylindrical, body partaccuratelytormed toapredetermined diameter and each having a conical end part concentricwith the body part and adapted to exactly fit the groove between twothread convolutions, and relatively adjustable supports for holding therespective pins at the same distance from a common supporting surface,the said supports comprising blocks one of which has an extensionprojecting through and fitting an aperture in the other.

3. In a gauge of the class described, the combination of two parallelpins each having a cylindrical body part accurately formed to apredetermined diameter and each having a conical end part concentricwith the body part and adapted to exactly fit the groove between twothread convolutions, relatively adjustable supports for holding therespective pins at the same distance from a common supporting surface,the said supports comprising blocks one of which has an extensionprojecting through and fitting an aperture in the other, and a screwcarried by the apertured block and fitting the extension of the otherblock for relatively adjusting the supports.

at. In gauge oil'the class described, the combination of two parallelpins each having a cylindrical body part accurately formed to apredetermined diameter and each having a. conical end part concentricwith the body part and adapted to exactly fit the groove between. twothread convolutions. relatively adjustable supports for holding therespective pins at the same distance from a common supporting surface,the said supports comprising blocks one of which has anextensionprojecting through and fitting an aperture in they other, andmeans carried by the apertured block for engag the extension of theother block to clamp the supports in adjusted position.

5. In a gauge of the class described. the combination of two parallelpins each having a cylindrical body part accurately formed to apredetermined diameter and each having a conical end part concentricwith the body part and adapted to exactly fit the groove between twothread convolutions. relatively adjustable supports for holding therespective pins at the same distance from a, con'unon supportingsurface.

the said supports comprising blocks one of which has an extensionprojecting through and fitting an aperture in the other, a screw carriedby the apertured block and fitting the extension of the other block forrelatively adjusting the supports, and means to take up any lost motionbetween. said. sup ports. a

6. In a gauge of the class described, the combination of two parallelpins each having a cylindrical body part accurately formed to apredetermined diameter and each having a conical end part concentricwith the body part and adapted to exactly fit the groove between twothread convolutions, relatively adjustable supports for holding therespective pins at the same distance from a common supporting surface,

the said supports comprising blocks one of which has an extensionprojecting through and fitting an aperture in the other, a screw carriedby the aperturcd block and fitting the extension of the other block forrela- FRANK O. HOAGLAND.

